I am responding to your letter of November 14, 1998
requesting that the National Bioethics Advisory Commission
discuss at its meeting in Miami this week the ethical, medical,
and legal concerns arising from the fusion of a human cell with a
cow egg.

The Commission shares your view that this development raises
important ethical and potentially controversial issues that need
to be considered, including concerns about crossing species
boundaries and exercising excessive control over nature, which
need further careful discussion. This is especially the case if
the product resulting from the fusion of a human cell and the egg
from a non-human animal is transferred into a woman's uterus and,
in a different manner, if the fusion products are embryos even if
no attempt is made to bring them to term. In particular, we
believe that any attempt to create a child through the fusion of
a human cell and a non-human egg would raise profound ethical
concerns and should not be permitted.

We devoted time at our meeting to discussing various
aspects of this issue, benefiting not only from the expertise of
the Commissioners, but from our consultation (via telephone) with
Dr. Ralph Brinster, a recognized expert in the field of
embryology, from the University of Pennsylvania. Also in
attendance at our meeting was Dr. Michael West, of Advanced Cell
Technology, who was given an opportunity to answer questions from
Commission members. As you know, however, the design and results
of this experiment are not yet publicly available, and as a
consequence the Commission was unable to evaluate fully its
implications.

As a framework for our initial discussion, we found it
helpful to consider three questions:

1. Can the product of fusing a human cell with the egg of a
non-human animal, if transferred into a woman's uterus,
develop into a child?

At this time, there is insufficient scientific evidence to
answer this question. What little evidence exists, based on
other fusions of non-human eggs with non-human cells from a
different species, suggests that a pregnancy cannot be
maintained. If it were possible, however, for a child to develop
from these fused cells, then profound ethical issues would be
raised. An attempt to develop a child from these fused cells
should not be permitted. This objection is consistent with our
views expressed in Cloning Human Beings, in which we concluded
that:

"at this time it is morally unacceptable for anyone in the
public or private sector, whether in a research or clinical
setting, to attempt to create a child using somatic cell
nuclear transfer cloning."

2. Does the fusion of a human cell and an egg from a non-human
animal result in a human embryo?

The common understanding of a human embryo includes, at
least, the concept of an organism at its earliest stage of
development, which has the potential, if transferred to a uterus,
to develop in the normal course of events into a living human
being. At this time, however, there is insufficient scientific
evidence to be able to say whether the combining of a human cell
and the egg of a non-human animal results in an embryo in this
sense. In our opinion, if this combination does result in an
embryo, important ethical concerns arise, as is the case with all
research involving human embryos. These concerns will be made
more complex and controversial by the fact that these hybrid
cells will contain both human and non-human biological material.

It is worth noting that these hybrid cells should not be
confused with human embryonic stem cells. Human embryonic stem
cells, while derived from embryos, are not themselves capable of
developing into children. The use of human embryonic stem cells,
for example to generate cells for transplantation, does not
directly raise the same type of moral concerns.

3. If the fusion of a human cell and the egg of a non-human
animal does not result in an embryo with the potential to
develop into a child, what ethical issues remain?

If this line of research does not give rise to human
embryos, we do not believe that totally new ethical issues arise.
We note that scientists routinely conduct non-controversial and
highly beneficial research that involves combining material from
human and other species. This research has led to such useful
therapies as: blood clotting factor for hemophilia, insulin for
diabetes, erythropoietin for anemia, and heart valves for
transplants. Combining human cells with non-human eggs might
possibly lead some day to methods to overcome transplant
rejections without the need to create human embryos, or to
subject women to invasive, risky medical procedures to obtain
human eggs.

We recognize that some of the issues raised by this type of
research may also be pertinent to stem cell research in general.
We intend to address these and other issues in the report that
you requested regarding human stem cell research.